Design considerations for core material selection and operating modes for a high frequency transformer used in an isolated DC/DC converter

Magnetic core materials are considered critical components that influence an isolated DC/DC converter´s dynamic response, efficiency and size. This paper illustrates the impact of core material choice in the design of a high frequency transformer for an isolated DC/DC converter for energy storage applications. The variation of the performance for different types of core material as well as the inter relationship between parameters (flux density, frequency, efficiency and size) is investigated. It is shown that, by summing up the loss surfaces of systems that (use different core materials) will result in a recommended core material map which can guide the designer towards the smallest losses that can be achieved in a given frequency and flux density range, which the designer can assign to their application. In addition, it will be investigated the variation of power loss with the loading factor, which is an important aspect in energy storage system since most systems will operate at reduced loading compared to the peak power capability, where the systems is designed from thermal point of view. In order to maximize transformer efficiency, adjustable voltage and current is considered and an analytical model to derive optimum operating point at a given frequency is derived. Exploration of finding the best operating point when frequency is also allowed to vary is also considered.